Most cases of the outbreak are concentrated in the southern U.S., with the highest concentration of cases (five each) in Georgia and Louisiana. The CDC announced the outbreak June 10. The outbreak has led to the death of 21-month-old Louisiana girl and several hospitalizations.

It has been six weeks since the onset of symptoms in the latest case, an indication the outbreak may be over, according to the CDC.

There still is no official source for the infections.

E. coli O145 belongs to a group called Shiga toxin-producing E. coli, or STECs. These strains can cause severe illness, such as bloody diarrhea and hemolytic uremic syndrome, a type of kidney failure.

The outbreak followed the implementation of new testing requirements for six non-O157 STECs (O145, O26, O45, O103, O111 and O121) which began June 4. Like E. coli O157:H7, the most common and serious strain of E. coli, these six STECs now are considered adulterants. Food contaminated with any of these strains is considered to be unfit for human consumption.